Mucosal immunity

Question 1

Barrier immunity

Answer 1

refers generally to immune systems associated with the skin and mucosal tissues

Question 2

The tissues of the mucosal immune system are

Answer 2

the lymphoid organs and cells associated with the gastrointestinal, respiratory, and urogenital tracts, as well as the oral cavity, pharynx, middle ear, and the glands associated with these tissues, such as the salivary glands and lacrimal glands. The lactating breast is also considered part of the mucosal immune system.

Question 3

Barrier organs are populated by

Answer 3

by innate and adaptive immune cells that interact with epithelium and secondary lymphoid tissue

Question 4

Microbiome

Answer 4

the collection of all microbes, such as bacteria, fungi, viruses, and their genes, that naturally live on our bodies and inside us.

Question 5

Adjacent IECs

Answer 5

form tight junctions that are essential to the function of the intestinal barrier and the regulation of movement of ions, solutes, and water across the intestinal epithelium

Question 6

Tight junctions

Answer 6

are primarily composed of claudins and occludins, transmembrane proteins that undergo homotypic adhesions between adjacent IECs near their apical surfaces to form a continuous ‘ribbon’ that seals the intercellular junction (middle panel).

Question 7

Epithelial cell types

Answer 7

Enterocytes
M cells
Goblet cells
Paneth cells
Enteroendocrine cells
Tuft cells
Transient amplifying cells
Stem cells

Question 8

Paneth cells

Answer 8

Only present in the SI. Antimicrobial peptides and SC niche. Highly specialized secretory epithelial cells located in the small intestinal crypts of Lieberkühn

Question 9

Tuft cells:

Answer 9

Specialized in response to Helminths. chemosensory cells in the epithelial lining of the intestines.

Question 10

Enteroendocrine cells:

Answer 10

Sense nutrients and release hormones and neurotransmitters to regulate nutrients absorption and satiety. Hormone-producing cells that are sprinkled throughout the gut epithelium.

Question 11

Mucus production roles

Answer 11

Produced by Goblet cells
Reduces mechanical stress
Trap microbes
Retain SIgA and AMPs
Colonization of commensals

Question 12

ILCs

Answer 12

Innate Lymphoid Cells
Three types: ILC1, ILC2 and ILC3

Question 13

ILC1

Answer 13

produce IFN-gamma – intracellular (virus and bacteria)

Question 14

ILC2

Answer 14

produce IL-13 – Helminth

Question 15

ILC3

Answer 15

produce IL-22 / IL-17A – Bacteria/fungi

Question 16

ILCs are

Answer 16

a family of lymphocytes comprising the innate counterparts of T cells. They are poised to secrete cytokines that respond swiftly to pathogenic tissue damage and shape subsequent adaptive immunity.While lacking antigen-specific receptors, ILCs detect changes in the microenvironment through receptors for cytokines that are released upon tissue damage, as well as a broad range of receptors for nutrient components, microbial products, lipid mediators, and neuronal transmitters

Question 17

ILCs are found

Answer 17

both lymphoid and non-lymphoid tissues

Question 18

Regulatory T cells

Answer 18

TREG
Defined by expression of Foxp3 (transcription factor)

Helps with tolerance and suppresses response by communicating to other immune cells

Question 19

TREG are made

Answer 19

Thymus during development (circulating)
in mesentyric Lymph Node through instruction by migrating dendritic cell

Question 20

Immune tolerance

Answer 20

Absence of inflammatory response to commensal microbiota and food components
Lamina propria constituents send transepithelial dendrites to sample the lumen
Environment enriched in IL10 and TGFB
Production of secretory IgA (SIgA)

Question 21

Type I (IFN-gamma, IL1b and IL18)immunity

Answer 21

Virus / intracellular bacteria

Question 22

Type II (Il-4, 5, and 13) immunity

Answer 22

Helminth/Allergens/Venoms

Question 23

Type III (IL-22, IL-17) immunity

Answer 23

Extracellular bacteria / fungi

Question 24

Type I immunity is activated

Answer 24

Activation of PRRs triggers
TLR activation induces IL23 production that induces IL17 and IL22 production by Th17 and ILCs. IL22 induces anitimicrobials expression by IECs and IL17 attract neutrophiles
NOD activation leads to inflammasome and IL1b and IL18 expression. That induces IFNg by ILCs.
DCs migrate mesenteric Lymph Nodes (mLN) for Th1 expansion
B cells IgG class switching